Morphological heterogeneity of esophageal carcinoma

To clarify the morphological heterogeneity of esophageal carcinoma, the adenocarcinomatous, basaloid, and sarcoma-like components of 178 esophageal carcinomas were studied with regard to histopathology, mucin histochemistry, immunohistochemistry, and ultrastructure. Adenocarcinomatous components with mucicarminophilic cells and/or glandular structures, basaloid components, and sarcoma-like components were found in 55 lesions (30.9%), 17 lesions (9.3%), and five lesions (2.8%) respectively. Carcinoembryonic antigen staining was positive in 52 lesions (29.2%), secretory component staining was positive in 15 (8.4%), and lactoferrin staining was positive in 12 (6.7%). Eight intraepithelial carcinomas were found to have no adenocarcinomatous components, and two intramucosal carcinomas had adenocarcinomatous components in the invasive portions. These findings strongly suggest that the adenocarcinomatous components do not arise from the ductal epithelium, but occur during the process of invasion. There were no significant clinicopathological differences between the carcinomas with adenocarcinomatous components and those without. Ultrastructurally, the adenocarcinomatous components were seen to possess intracellular microcysts, intercellular lumina, and bundles of tonofilaments, having features of both glandular and squamous epithelia. On the basis of the concept that the basaloid components are histological variants of squamous cell carcinoma and that sarcoma-like components arise from mesenchymal metaplasia of squamous cell carcinoma, it is possible that the three components may originate from the squamous component. The present study thus demonstrated a high incidence of histological variation among esophageal carcinomas.